The object of the proposed research project is to study the role of calcium in the secretory process of salivary glands. The in situ characteristics of calcium influx and efflux during rest and secretion will be determined by Ca45 perfusion studies, and the kinetic parameters of calcium movement will be correlated with various parameters of the salivary secretion. Calcium-45 labeling studies will be used to follow the intracellular movement of calcium during rest and secretion. The subcellular organelles responsible for sequestration and release of that fraction of the total gland calcium which is associated with secretion will be identified, and the subcellular origin of the centrifugal fractions will be determined by enzymatic markers. The characteristics of the calcium sequestering and the calcium-releasing organelles will be determined in vitro using the Ca45-millipore filtration technique. The kinetics and mechanisms of sequestration and release and the effects of pharmacologic agents known to affect salivary gland function will be studied.